True, they wouldn't even need to militarily invade us. Trump could just ratchet up the pressure like he's doing with Greenland right now.
Greenland is not being surrendered by the locals or the Danes.
The added pressure is a threat (unlikely to be acted on)
But even if it were, look at the on-the-ground impacts in Europe and Canada to date. They are modest, most sectors are actually exempt, and/or individual products or classes of products are exempt.
Yes, the U.S. could apply much greater pressure, but they likely won't. Look at what happened when Americans balked at paying tariffs on Chinese-made Iphones.
Trumps tariffs have more holes than Swiss Cheese.
That's not to suggest they aren't disruptive and material in select cases (ask our Steel industry); but they are also remarkably ineffective at achieving their stated goals (reshoring U.S. jobs), meanwhile they are proving quite successful at stoking U.S. inflation.
The headline numbers still aren't too bad (2.7% CPI) but look under the hood, and find food and shelter up 3.1%.
The latter should be all but impossible if you believe the rhetoric on the U.S.population shrinking via deportation, self-deportation, and cuts to immigration/foreign students.
But if you jack the cost of building materials and agricultural inputs like Potash........
*****
Suffice to say, a boots-on-the-ground U.S. invasion is not coming. There's always 1 in a million odds of anything; but its beyond improbable.
We needn't address a war games scenario that is not in the offing. (not to suggest the military shouldn't do so, but for the public, its a bit of silly exercise)
The economic issues of the disruption to date are very manageable and in fact, show significant sign of some benefits to Canada, though those are at least partially things happening for other reasons, anyway, that have just been slightly accelerated) .
(as example, our reliance on U.S. produce, even off-season, is declining), both due to greater domestic production, particularly of salad greens, and berries, but also due to sourcing shifts, picking up products from Europe and Latin America.
That said,, we remain dependent on U..S sources for up to 55% of produce in the off-season (down from high 60s) and getting that number much lower will require further investments over time.
We certainly should make such investments to be more sovereign and more resilient and my industry contacts suggest this is likely, though as much motivated by concern over climate as tariffs, with California and Arizona facing increasing water difficulties, as well as Canada's increasing leadership in greenhouse growing.